Sampling and Analysis of Volatile Organic Compounds Emitted from Leaded and Unleaded Gasoline Powered Motor Vehicles

Abstract

The C₃-C₁₀ volatile organic compounds (VOC) present in leaded and unleaded gasoline and the exhausts resulting from catalyst and noncatalyst vehicles tested with the European driving cycle have been analyzed in the present study. These tests have shown that the exhausts are enrichedin prop-1-ene, n-but-1-ene, benzene, 2,2,4-trimethylpentane, ethylbenzene, styrene, o-xylene and naphthalene. Styrene allows the differentiation between emissions from catalyst and noncatalyst vehicles. Most of these compounds are highly reactive to photooxidation. Theirformation and increase leads to more reactive VOC mixtures than those initially present in the gasolines.A higher proportion of aromatic compounds, includingbenzene, is observed in the catalyst vs. thenoncatalyst vehicles. However, the total noncatalystVOC yield is more than two times higher than that ofthe catalyst vehicles involving, in terms of absoluterelease, that the noncatalyst vehicles are responsiblefor higher emissions of aromatic hydrocarbons.The high relative proportion of aromatic VOC in theexhausts of both vehicles represents a majordifference between the results of the European drivingcycle and the VOC emissions observed in other tests(57–69% vs. 18–30%, respectively). The highabundances of aromatic compounds in the European testvehicle emissions are in good correspondence with thehigh proportion of these hydrocarbons in the urban airof cities such as Barcelona.